Electric-field-induced changes in fluorescence decay and spectrum of tris(8-hydroxyquinoline)aluminum in a polymer film

Electric field effects on absorption and emission spectra and emission decay have been examined for tris(8-hydroxyquinoline)aluminum (Alq3) doped in a poly(methyl methacrylate) film. Emission spectra as well as absorption spectra of Alq3 exhibit the so-called Stark shift in the presence of external electric field, and a significant change in electric dipole moment takes place following the optical transition. Fluorescence of Alq3 also shows the electric-field-induced quenching, which is confirmed to originate from the field-induced increase in intramolecular non-radiative decay at the emitting state by the direct measurements of the field-induced change in fluorescence decay profile.